Fang Daliang, Wang Yanlei, Liu Xizheng, Yu Jia, Qian Cheng, Chen Shimou, Wang Xi, Zhang Suojiang
Beijing Key Laboratory of Ionic Liquid Clean Process, CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering , Chinese Academy of Sciences , Beijing 100190 , China.
University of Chinese Academy of Sciences , Beijing 100049 , China.
ACS Nano. 2019 Feb 26;13(2):1563-1573. doi: 10.1021/acsnano.8b07491. Epub 2019 Jan 11.
Despite their high theoretical capacity density (1675 mAh g), the application of Li-S batteries has been seriously hindered by the shuttle effect of polysulfides. Here, inspired by the working principle of natural spider webs, we synthesized a spider-web-like nanocomposite in which many hollow mesoporous silica (mSiO) nanospheres/Co nanoparticles were threaded by interconnected nitrogen-doped carbon nanotubes (NCNTs). Then the nanocomposite (denoted as Co/mSiO-NCNTs) was coated on the commercial separator by a simple infiltration to mitigate the above issue. The intimate combination of three-dimensional conductive networks (NCNTs) with abundant polysulfide adsorbent sites (SiO and N)/polysulfide conversion catalysts (Co and Co-N species) allows the Co/mSiO-NCNTs coating layer to not only effectively capture polysulfides via both physical confinement and chemical bonding but also accelerate the redox kinetics of polysulfides significantly. Furthermore, the combination of ex situ experiment and theoretical calculation demonstrates that the reversible adsorption/desorption of polysulfides on mSiO nanospheres benefits uniform deposition of LiS/LiS on the conductive networks, which contributes to long-term cycling stability. As a result, Li-S batteries with Co/mSiO-NCNTs-coated separators exhibited both excellent cycling stability and rate performance.
尽管锂硫电池具有较高的理论容量密度（1675 mAh g），但其应用却因多硫化物的穿梭效应而受到严重阻碍。在此，受天然蜘蛛网工作原理的启发，我们合成了一种类似蜘蛛网的纳米复合材料，其中许多中空介孔二氧化硅（mSiO）纳米球/钴纳米颗粒被相互连接的氮掺杂碳纳米管（NCNTs）贯穿。然后通过简单的浸润法将该纳米复合材料（记为Co/mSiO-NCNTs）涂覆在商用隔膜上，以缓解上述问题。三维导电网络（NCNTs）与丰富的多硫化物吸附位点（SiO和N）/多硫化物转化催化剂（Co和Co-N物种）的紧密结合，使得Co/mSiO-NCNTs涂层不仅能通过物理限制和化学键合有效地捕获多硫化物，还能显著加速多硫化物的氧化还原动力学。此外，非原位实验与理论计算相结合表明，多硫化物在mSiO纳米球上的可逆吸附/解吸有利于LiS/LiS在导电网络上的均匀沉积，这有助于实现长期循环稳定性。结果，采用Co/mSiO-NCNTs涂覆隔膜的锂硫电池展现出优异的循环稳定性和倍率性能。
